Ichinose A, Espling E S, Takamatsu J, Saito H, Shinmyozu K, Maruyama I, Petersen T E, Davie E W
Department of Biochemistry, University of Washington, Seattle 98195.
Proc Natl Acad Sci U S A. 1991 Jan 1;88(1):115-9. doi: 10.1073/pnas.88.1.115.
The gene coding for plasminogen has been compared with several abnormal genes from Japanese patients by the polymerase chain reaction and DNA sequence analysis. Two types of abnormal genes coding for plasminogen were identified in these patients. In the type I mutation, a guanosine in GCT coding for Ala-601 near the active-site histidine was replaced by an adenosine resulting in ACT coding for threonine. This mutation was also shown by the loss of a cleavage site for Fnu4HI endonuclease, a restriction enzyme that recognizes GCTGC but not ACTGC. In the type II mutation, a guanosine in GTC coding for Val-355 was replaced by a thymidine resulting in TTC coding for phenylalanine. This change was readily shown by digestion with Ava II endonuclease, a restriction enzyme that recognizes GGTCC and not GTTCC. The type I mutation has been found to be identical to a plasminogen variant identified in Japanese patients by amino acid sequence analysis and also detected by isoelectric focusing, whereas the type II mutation is a unique amino acid substitution in the connecting region between the third and fourth kringles in plasminogen. DNA sequence analysis also revealed that the abnormal genes carry several silent nucleotide substitutions located primarily within introns and 5' and 3' flanking regions.
通过聚合酶链反应和DNA序列分析，已将编码纤溶酶原的基因与来自日本患者的几个异常基因进行了比较。在这些患者中鉴定出了两种编码纤溶酶原的异常基因。在I型突变中，编码活性位点组氨酸附近Ala-601的GCT中的鸟苷被腺苷取代，导致ACT编码苏氨酸。这种突变也表现为Fnu4HI核酸内切酶（一种识别GCTGC但不识别ACTGC的限制性酶）切割位点的缺失。在II型突变中，编码Val-355的GTC中的鸟苷被胸苷取代，导致TTC编码苯丙氨酸。这种变化通过用Ava II核酸内切酶消化很容易显示出来，Ava II核酸内切酶是一种识别GGTCC而不识别GTTCC的限制性酶。已发现I型突变与通过氨基酸序列分析在日本患者中鉴定出的一种纤溶酶原变体相同，并且也通过等电聚焦检测到，而II型突变是纤溶酶原第三和第四kringle之间连接区域中的独特氨基酸取代。DNA序列分析还显示，异常基因携带几个主要位于内含子以及5'和3'侧翼区域的沉默核苷酸取代。
